Benzie John A H
Australian Institute of Marine Science, PMB No. 3, Townsville MC, Queensland, 4810, Australia.
Evolution. 1999 Dec;53(6):1782-1795. doi: 10.1111/j.1558-5646.1999.tb04562.x.
Spatial variation in allelic frequencies at nine allozyme loci were assayed in 20 populations of the crown-of-thorns starfish, Acanthaster planci, collected throughout the Pacific and Indian Oceans. These data were analyzed together with published data, for the same loci, from an additional 19 populations, giving a total sample size of approximately 1800 individuals. There was a marked discontinuity between the Indian and Pacific Ocean populations, but those off Western Australia and from the Southeast Asian region had a strong Pacific affinity. The genetic groups were congruent with the distributions of two color morph groups: gray-green to red-brown forms in the Pacific and a blue to pale red form in the Indian Ocean. These patterns of genetic structure are similar to those described for the starfish Linckia laevigata, which has similar life-history characteristics. Vicariant events may have influenced some populations within the Pacific, but the allozyme data cannot resolve the effects of these events clearly. Patterns of variation within regions were consistent with isolation by distance, but, at larger scales, were obscured by regional vicariance and some outliers, particularly by apparently high levels of gene flow between Japan and the Great Barrier Reef, Australia. Apparent gene flow between population pairs was not closely related to present-day ocean currents. The results demonstrate a strong influence of allopatric separation on genetic divergence at large geographic scales, but also show evidence of slow rates of change in gene frequencies consistent with the large population sizes of this species. Low levels of divergence between groups demonstrate the genetic structure is recent (Pleistocene) and are likely responses to changes in climate and sea level.
在整个太平洋和印度洋采集的20个棘冠海星种群中，检测了9个等位酶位点的等位基因频率的空间变异。这些数据与已发表的来自另外19个种群的相同位点的数据一起进行了分析，样本总数约为1800个个体。印度洋和太平洋种群之间存在明显的间断，但西澳大利亚沿海和东南亚地区的种群与太平洋有很强的亲缘关系。遗传群体与两种颜色形态群体的分布一致：太平洋地区为灰绿色到红棕色形态，印度洋为蓝色到浅红色形态。这些遗传结构模式与具有相似生活史特征的海星多腕葵花海星所描述的模式相似。地理隔离事件可能影响了太平洋内的一些种群，但等位酶数据无法清楚地解析这些事件的影响。区域内的变异模式与距离隔离一致，但在更大尺度上，被区域地理隔离和一些异常值所掩盖，特别是日本和澳大利亚大堡礁之间明显高水平的基因流。种群对之间明显的基因流与当今的洋流没有密切关系。结果表明，异域隔离在大地理尺度上对遗传分化有很大影响，但也显示出基因频率变化速率缓慢的证据，这与该物种的大种群规模一致。群体间低水平的分化表明遗传结构是近期（更新世）形成的，可能是对气候和海平面变化的反应。
